JP2002242580A - Tunnel construction method, drainage method and tunnel - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a tunnel construction method and the like that collects water in a ground and effectively lowers the groundwater level of the ground around the tunnel. SOLUTION: On both sides of a planned tunnel position 3, an improved body 7 which reaches a gravel layer 21 is provided as a water impervious wall against spring water from the ground, and a drain tube 1
7 is provided to collect and drain spring water from the gravel layer 21 to lower the groundwater level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel construction method, a drainage method, and a tunnel.

[0002]

2. Description of the Related Art Conventionally, when the NATM method is applied to a ground including groundwater, if a gravel layer or the like exists in front of a face, spring water will be generated during construction, and the construction of a precedent work may be incomplete. , And the face becomes unstable. Therefore, the advantages of auxiliary construction methods such as pre-installation work and groundwater countermeasure work are combined to maintain the stability of the top of the mountain and the face.

[0003]

However, depending on the location of the tunnel plan, it is difficult to take countermeasures against groundwater from above the ground, such as the deep well method.

[0004] The present invention has been made in view of such a problem, and its object is to collect water in the ground,
An object of the present invention is to provide a tunnel construction method, a drainage method, and a tunnel that effectively lower the groundwater level of the ground around the tunnel.

[0005]

According to a first aspect of the present invention, there is provided a method of constructing a tunnel for alternately performing excavation and support operations, wherein a ground improvement body is provided on both sides of a planned tunnel position. And a step of providing an auxiliary work and a drain pipe above the planned tunnel position. In the first invention, a ground improvement body is provided on both sides of the planned tunnel position, an auxiliary work and a drainage pipe are provided above the planned tunnel position, and the step of supporting and excavating is repeated. Groundwater around the site of the planned tunnel will be blocked by the ground improvement body and auxiliary works, and the drainage pipe will collect and discharge spring water from the ground.

A second invention is a drainage method for draining spring water from the ground near the planned tunnel position, wherein the step of drilling holes in the ground and installing a steel pipe provided with holes is provided. A step of inserting a pipe into the interior, a step of filling the gap between the ground and the steel pipe, the steel pipe and the pipe with a filler, and a step of connecting a water pipe to the pipe,
The drainage method is characterized in that spring water from the ground is discharged from the pipe through the water pipe. Second
According to the invention, a perforated steel pipe is installed in the ground, the pipe is inserted into the steel pipe, the gap between the ground and the steel pipe, and the gap between the steel pipe and the pipe are filled with the filler, and the water pipe is connected to the pipe. Spring water from the ground is collected at the tip of the pipe and discharged through the inside of the pipe and water pipe.

[0007] A third invention is a tunnel constructed by the tunnel construction method of the first invention.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view after the improvement body 7 is installed. The improved body 7 is formed by using, for example, the cross jet method, and improves the ground at the side of the planned tunnel position. First, prior to excavation at the planned tunnel position 3, a drilling machine 5 is installed on the ground surface 1 as shown in FIG. Then, after drilling the guide hole 6 to a predetermined depth by the drilling machine 5, the drilling machine 5 is removed and a forming machine is installed. further,
A triple pipe is inserted into the guide hole 6, and the ground is cut to discharge the slime while filling the hardening material to construct the improved body 7.

FIG. 2 is a sectional view taken along line AA of FIG. 3, and FIG.
0 is a side view. As shown in FIGS. 2 and 3, a mirror reinforcement 9 is applied to stabilize the face 15. For the mirror reinforcement 9, for example, after spraying concrete on the face 15, a rodin jet method is used. Rodin jet method is to cut and mix the ground by drilling the ground to a predetermined depth and then ejecting the hardened material from the tip of the rod while injecting it at ultra-high pressure to create a columnar improved body. Things. When water is discharged from the drilled hole, if necessary, measures against spring water such as stabilizing the hole wall by injecting a water glass-based material instead of cement milk are taken.

Then, from the face 15 to the planned tunnel position 3
A hole is drilled in the upper part of, and the precedenter 11 is installed. First work 1
For example, a rodin tube method is used for 1. The rodin tube method is to build a steel pipe for injection into the ground and inject the injected material to improve the ground. Urethane or cement-based injection materials are selected based on the amount of spring water from the built steel pipes. As shown in FIGS. 2 and 3, a plurality of preloaders 11 are provided at predetermined intervals toward the ground above the tunnel 50.

Next, a drain tube 17 is installed above the planned tunnel position 3 from the face 15. FIG. 4 is a detailed view of the drain tube 17. First, the ground is drilled from the face 15 by extending the excavation length of the precedenter 11 by several meters, and a steel pipe 33 is driven. The steel pipe 33 has a plurality of holes 4.
1 and the length is equal to or longer than that of the precedent 11. Then, a drain pipe 29 such as a vinyl chloride pipe is installed inside the steel pipe 33.

The drainage pipe 29 is composed of a water guide part 29a inside the steel pipe 33 and a water collector part 29b ahead of the water guide part 29a.
It has a hole 35 near the tip of a. The tip of the water collecting part 29b reaches the gravel layer 21. When the gravel layer 21 comes down inside the face 15, the location of the drainage pipe 29 is shifted downward as appropriate.

Further, the mouth of the steel pipe 33 is caulked,
Filler 3 is placed in the gap between drain pipe (water guide) 29a and steel pipe 33.
Inject 7 The filling is completed when the filler 37 is filled to the tip of the steel pipe 33 and flows backward through the hole 35 of the drain pipe 29. Since the steel pipe 33 has the hole 41 over the entire length, the gap between the steel pipe 33 and the ground 42 is also filled with the filler 37a. As the filler 37 and the filler 37a, a cement hardening material or the like is used. Then, the water guide pipe 40 is connected to the face 15 side of the drain pipe (water guide section) 29a.

By setting the length of the steel pipe 33 to be equal to or longer than the length of the preloader 11, the installation section of the preloader 11 becomes an impermeable section. The filler 37 and the filler 37a are formed by the spring water from the gravel layer 21 and the gap between the ground 42 and the steel pipe 33 and the steel pipe 3
It is prevented from flowing into the face 15 from the gap between the drainage pipe 3 and the drain pipe 29. The spring water from the gravel layer 21 is drained from the drainage pipe (water collecting section) 29.
The water is collected at b, and is discharged from the water guide pipe 40 through only the inside of the drain pipe 29. The temporal change of the groundwater level due to the action of the drain tube 17 is observed at the observation well 25.
Note that, as shown in FIGS.
Is provided toward the ground above the tunnel 50.

The improved body 7 is continuously formed on both sides of the planned tunnel position 3, and extends from the clay layer 23 on the side of the planned tunnel position 3 to the debris layer 21 across the stratum boundary 19. Clay layer 23 has poor water permeability, and
By extending the flow to the contaminated layer 21 above the planned tunnel position 3, the flow of the groundwater can be suppressed, and the permeation of the groundwater from the face 15 or the top end of the face 15 can be prevented. As described above, the improved body 7 supports the shoring 13, blocks the groundwater of the permeable layer 21, and lowers the permeability coefficient.

The pre-installation work 11 prevents collapse of the ground (clay layer 23 and gravel layer 21) above the planned tunnel position 3;
Blocks groundwater and reduces permeability. The drain tube 17 drains the groundwater of the gravel layer 21 and lowers the groundwater level.

Assuming that spring water at the planned tunnel position 3 is Q, it can be expressed as Q = A × k × h / L. A is the area in contact with the permeability zone, k is the permeability coefficient of the zone formed by the auxiliary method, h is the height of the groundwater above the zone formed by the auxiliary method, and L is the thickness of the zone formed by the auxiliary method. . Here, the auxiliary construction method is the improved body 7 and the precedent construction 11. The improved body 7 and the preform 11 form a zone (thickness L) where k is reduced. The drain tube 17 reduces h. Therefore, spring water Q decreases.

The construction of the tunnel 50 proceeds as shown in FIG. FIG. 5 is a cross-sectional view of the upper half portion 47 of the tunnel at the time of excavation. The upper half of the planned tunnel position 3 is excavated using the excavator 45, and the shoring 13 is built. FIG. 6 is a sectional view of the lower half portion 51 of the tunnel at the time of excavation. The lower half of the planned tunnel position 3 is excavated using the excavator 49, and the shoring 55 is built.

FIG. 7 is a sectional view when the invert 53 is constructed, and FIG. 8 is a sectional view when the lining concrete 55 is constructed. An invert 53 is constructed below the lower half portion 51 of the tunnel, and lining concrete 55 inside the tunnel 50 is cast to complete the tunnel 50.

As described above, the drainage tube 17 is provided to drain the spring water from the gravel layer 21 so that the face 15
From spring water. In addition, by providing the improved body 7 as a water impervious wall on both sides of the tunnel planning position 3, the section of the precedent 11 can be made into an impermeable zone, and supply of groundwater to the ground above the planning tunnel position 3 can be achieved. Can be shut off.

In the present embodiment, the improved body 7 reaches the gravel layer 21, but may have a length sufficient to support the support 13. That is, the support 1 of the precedent 11
Reach level 3 riding. Also, installation of the improved body 7,
Each of the auxiliary construction methods such as the precedenter 11 and the mirror reinforcement 9 may be replaced with an equivalent auxiliary construction method.

[0022]

As described above in detail, according to the present invention, a method of constructing a tunnel, a draining method, and a method of collecting water in a ground and effectively lowering the groundwater level of the ground around the tunnel are effectively provided. Can provide a tunnel.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view after an improved body 7 is installed.

FIG. 2 is a sectional view taken along line AA of FIG. 3;

FIG. 3 is a side view of the tunnel 50 after installation of the precedenter 11 and the drain tube 17;

FIG. 4 is a detailed view of a drain tube 17;

FIG. 5 is a sectional view of the upper half portion 47 of the tunnel at the time of excavation.

FIG. 6 is a cross-sectional view of the lower half portion 51 of the tunnel at the time of excavation.

FIG. 7 is a cross-sectional view when the invert 53 is constructed.

FIG. 8 is a cross-sectional view when lining concrete 55 is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ground surface 3 ... Planned tunnel position 7 ... Improved body 11 ... Preceding work 13 ... Supporting work 15 ... Face face 17 ... Drainage tube 21 ... Brake layer 27 Span length 29a, 29b Drain pipe 33 Steel pipe 41 Hole

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shigeo Hosokawa 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Inside Kashima Construction Co., Ltd. (72) Inventor Hiroshi Oya 1-2-7 Moto-Akasaka, Minato-ku, Tokyo No. Kashima Construction Co., Ltd. (72) Inventor Harutaka Takahashi 1-2-7 Moto Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Mitsugu Iwata 1-2-2 Moto-Akasaka, Minato-ku, Tokyo No. 7 F-term in Kashima Construction Co., Ltd. (reference) 2D054 AC15 AC20 AD23 FA02 FA06 FA07

Claims (8)

[Claims] 1. A method for constructing a tunnel in which excavation and support operations are alternately performed, wherein a ground improvement body is provided on both sides of a planned tunnel position, and an auxiliary work and a drain pipe are provided above the planned tunnel position. A method for constructing a tunnel, comprising the steps of: 2. The tunnel construction method according to claim 1, wherein an upper portion of the ground improvement body reaches a level at which the support of the precedent is mounted. 3. The tunnel construction method according to claim 1, wherein an upper portion of the ground improvement body reaches a spring layer. 4. The tunnel construction method according to claim 1, wherein the auxiliary work is a precedent work. 5. The tunnel construction method according to claim 1, wherein the length of the drainage pipe in the ground is longer than the length of the auxiliary work. 6. A draining method for draining spring water from a ground near a planned tunnel position, wherein a hole is drilled in the ground and a steel pipe provided with a hole is provided, and a pipe is provided inside the steel pipe. And filling the gap between the ground and the steel pipe, the steel pipe and the pipe with a filler, and connecting a water guide pipe to the pipe. A method for draining water, wherein water is discharged from the pipe along the water pipe. 7. The draining method according to claim 5, wherein a tip of the pipe reaches the spring layer. 8. A tunnel constructed by the tunnel construction method according to claim 1.